Process for converting water-repellent surfaces of plastic into water-attractive surfaces



United States Patent ABSTRACT OF THE DISCLOSURE This application relatesto an electroless deposition, particularly one having magneticproperties, on a medium, and particularly a medium such as polyethyleneterephthalate. The invention also relates to a method of preparing themedium such as polyethylene terephthalate for the deposition of themagnetic material and for thereafter depositing the magnetic material onsuch medium.

This is a continuation-in-part of application Ser. No. 414,399 (nowabandoned), filled Nov. 27, 1964, which in turn was acontiuuation-in-part of application Ser. No. 212,442 (now abandoned),filed July 25, 1962, by George Wilhelm for a Process for ConvertingWater Repellent Surfaces of Plastic into Water Attractive Surfaces.

This invention primarily relates to converting waterrepellent surfacesof plastic material to water-attractive surfaces. In particular, thisinvention concerns converting water-repellent surfaces of plasticmaterials into waterattractive surfaces upon which magnetic memorymaterials may be deposited with superior results by elec troless orother methods of deposition;

Hitherto, previous methods of treating plastic materials for use as abase for magnetic memory materials have had disadvantages of high costsand poor results. In particular, such methods result in damage to theplastic materials and also result-in a relatively low signalto-noiseratio of the magnetic materials deposited on such abase.

It is, therefore, an object of my invention to provide an improvedprocess for converting Water-repellent surfaces into water-attractivesurfaces without damage to the plastic materials. 3

"Another object of my invention is to provide such a process which isrelatively inexpensive and uses readily avialable material. t

A further object of my invention is to provide such a process which issubstantially more effective than hitherto known methods for convertingplastic materials to receive deposits of magnetic memory. materials.

A still further object of my invention is to provide a favorableincrease of the signal-to-noise ratio of magnetic memory materialsdeposited on plastic film treated by my new process, particularly if themagnetic domains are oriented during deposition in a strong magneticfield and better wear characteristics.

Other objects and advantages of this invention will become more readilyapparent with reference to the following discussion.

The following is an embodiment of my invention as performed on plasticfilm consisting of a polymer which is the reaction product ofterephthalic acid and polyhydric alcohols. This plastic film is marketedunder the trademark Mylar, and constitutes polyethylene terephthalateand is provided in the form of a roll of film in different thicknessesupon which magnetic memory materials may be deposited by electroless orother methods.

ICE

This plastic film is water repellent and is converted to awater-attractive film by my new process which uses the action of aphenol in an alkaline medium, preferably strongly alkaline. Any phenoliccompound which is water soluble may be used..The desired alkalinity maybe produced with any of the water-soluble hydroxides or carbonates ofalkali or alkaline earth metals, or mixtures of them. i

I have found that such action of a phenol is an alkaline medium isenhanced by the addition of a water-soluble sulfonic or a water-solublesulfinic acid. Also, any watersoluble salt of a sulfonic or sulfinicacid may be used such as, for example, formaldehyde-sulfoxylate sodium.A suitable range of concentration of each of these rea gents consists offrom 0.1 to 1.0 mole per liter of each of the phenolic compound,sulfonic or sulfinic acid, or water-soluble saltof either, and thewater-soluble hydroxide or carbonate, or both, as the case may be.

Example 1 To carry out a preferred embodiment of my process, 24 grams ofphenol is dissolved in milliliters of a 40% by weight sodium hydroxidesolution. This mixture is heated to a temperature ranging from 70 to 95C., and then 20 grams of formaldehyde-sulfoxylate sodium is added. Theresulting mixture is kept at a temperature from to 100 C. for from 5 to30 minutes with stirring, after which time a white slurry is formed in aviscous solution. Upon cooling to 20 C., the slurry solidifies into ahard mass with long crystals.

In the preparation of the plastic film, the slurry formed as describedabove is heated to a temperature from 60 to 100 C. and a section of theplastic film is immersed for a period of time from 5 seconds to 5minutes depending upon and varying inversely with the temperature in theslurry, and is then removed. I have found that 30 seconds time ispreferable at C. The plastic film is then washed at least one minutewith continuously runing water at the rate of one gallon per minute toremove any traces of the slurry remaining thereon. At this point, theplastic film which was water repellent is now water attractive and holdswater on its surfaces. Further, the plastic film has not been damagedand after magnetic memory materials are subsequently deposited on it, ahigher signal-to-noise ratio will be produced as a result of treatmentof the film by my process.

I have found that a further step of treating the now water-attractiveplastic film with a water solution of nitric acid will improve theadhesion of magnetic memory materials to the plastic film when depositedthereon by electroless or other methods of deposition. I have found thata Water solution of 70% nitric acid at room temperature such as 20 C.for 10 seconds to one minute of contact time with the film is adequate,as well as a water solution of 50% nitric acid in contact with thewater-attractive film for 5 minutes at room temperature.

Further preparation of the now water-attractive plastic film beforedepositing magnetic memory materials is conventional and involvesimmersing the plastic film for 60 seconds in a reduction bath consistingof grams of stannous chloride, a liter of distilled water and 200milliliters of 38% hydrochloric acid. Next, the plastic film iscarefully washed with water to remove all traces of the reduction bath.The resulting plastic film is then immersed for one minute in anactivating solution maintained at 60 C. The activating solution is madeup of Water and palladium chloride with a concentration of 0.05 gram ofpalladium chloride per liter of distilled water adjusted to a pH of 3with hydrochloric acid.

The plastic film is now ready to be plated by electroless or othermethods with various materials suitable for use as magnetic memorymaterials.

When magnetic memory materials are deposited on plastic-film which hasbeen treated by my new process, such materials will have a significantlyhigher signal-tonoise ratio than when they are plated on plastic filmnot so treated, and this higher signal-to-noise ratio is due solely tothe treatment of the plastic film by my new process when orientation isused. The superior characteristics of the final product are also, tosome extent, attributable to the absence of damage to the plastic filmwhen treated with my new process.

The following are examples illustrating the electroless plating ofvarious magnetic memory materials on plastic film treated by my newprocess.

Example 2a An electroless plating solution is prepared by dissolving 80grams of sodium citrate, 40 grams of potassium sodium tartrate, 10 gramsof sodium hypophosphite, 60 grams of nickelous sulfate and 30 grams offerrous sulfate in 700 milliliters of distilled water by stirring andheating. The pH of the solution is adjusted to pH 9 with concentratedammonia solution. The solution is heated at 90 C. while the treatedplastic film is immersed in the solution for one to three minutes and isthen removed and washed with water. As a result, the plastic film hasbecome plated with a nickel-iron alloy having an increasedsignal-to-noise ratio over that obtained with other methods of preparingthe plastic film.

Example 2b The same procedure is used as in Example 2a except that theelectroless plating solution is made up of 80 grams of sodium citrate,40 grams of potassium sodium tartrate, 10 grams of sodium hypophosphite,10 grams of ethylene-diamine-tetra-acetic acid-sodium salt, 60 grams ofcobalt sulfate, and 10 grams of ferrous sulfate. After treatment withthis electroless plating solution, as described in Example 2a, theplastic film has become plated with a deposit of a cobalt-iron alloyhaving an increased signal to noise ratio over that obtained with othermethods used to prepare plastic films such as Mylar for electroless orother types of plating with magnetic memory materials.

Example 2c The same procedure of Example 2a is used except that theelectroless plating solution is made up of 80 grams of sodium citrate,40 grams of potassium sodium tartrate, 10 grams of urea, 10 grams ofsodium hypophosphite, 100 grams of cobalt sulfate and 4 grams ofmanganous sulfate.

After treatment with this solution as described in Example 2a theplastic film becomes plated with a deposit of a cobalt-manganese alloyhaving an increased signalto-noise ratio over that obtained with othermethods used to prepare plastic films such as Mylar for electroless orother types of plating with magnetic memory materials.

The plastic material such as the poly-terephthalates may also beprepared by a modified method such as discussed below. This modifiedprocess actually constitutes the preferred embodiment. As a first stepof this modified method, phenol and water are mixed in the ratio of 60to 70 parts by weight of phenol to 30 to 40 parts by weight of water,which may be tap water. The plastic material such as the polyethyleneterephthalate in the form of a thin tape is then disposed in a bath ofthe phenol solution in water for a suitable period of time such as aperiod between 5 seconds and one minute and at a suitable temperaturesuch as a temperature between forty degrees centigrade and sixty fivedegrees centigrade. The amount of time for subjecting the plasticmaterial such as the polyethylene terephthalate tape to the phenolsolution is preferably between to 30 seconds.

A wetting agent may also be included in the solution in a suitableamount such as 0.05 to 2 milliliters of the Wetting agent to one gallonof water before the water is mixed with the phenol. A suitable wettingagent may be designated as MonawetMo7OE marketed by Mona Industries ofPaterson, N]. This wetting agent may comprise approximately 70% ofsodium di-octyl succinate in a solution of approximately 11% ethylalcohol and approximately 19% water.

The phenol in the water solution tends to etch the surface of theplastic material such as the polyethylene terephthalate tape. Thewetting agent in the solution increases the mixing of the phenol withthe Water so as to enhance the etching action of the phenol on thesurface of the plastic material. If the amount of phenol should be madeexcessively high in the water solution, the phenol will tend tocrystallize. on the surface of the plastic material and produceinordinately great etching action on the tape and provide problems inobtaining a removal of the phenol from the tape in successive steps ofthe process. Certain solvents such as xylene may also be included in thesolution to prevent crystallization of the phenol but these solventssometimes present a problem of removal in subsequent steps.

The surface of the film is not delustered even after the film has beensubjected to the phenol solution described in the previous paragraph.The surface of the film is not delustered since it has a smooth andshiny appearance even after it has been treated with the phenolsolution. 'A smooth finish of the film is important since the layer ofmagnetic material subsequently deposited on the film will not have auniform separation from a magnetic head at successive positions alongthe film if the finish of the film is not smooth. This will preventinformation from being accurately recorded on the film and subsequentlyreproduced from the film.

As a next step in the modified process, the excess of phenol on thesurface of the plastic material such as the polyethylene terephthalateis removed by a suitable solution. For example, a diluted solution ofsodium hydroxide having a concentration in the order of ten percent tothirty percent in water can be used at room temperature to wash thephenol into the solution. Preferably, a twenty percent solution ofdiluted sodium hydroxide in water is used at room temperature. Actually,any alkali capable of dissolving phenol to produce phenolate can be usedsince phenolate is water soluble and becomes dissolved into the watersolution. Other solvents such as ether and acetone can also be used towash the phenol from the surface of the plastic material such as thepolyethylene terephthalate. When a diluted solution of sodium hydroxidein water is used, the solution can be applied to the surface of the tapefor a considerable period of time such as a period between one minuteand ten minutes.

The surface of the plastic material such as polyethylene terephthalateis treated with concentrated sodium hydroxide as a next step in themodified process. The concentrated sodium hydroxide may be in a watersolution with a. concentration of thirty percent to forty percent ofsodium hydroxide in the solution. The surface of the plastic materialsuch as the polyethylene terephthalate is disposed in a solution of theconcentrated sodium hydroxide at an elevated temperature such as betweensixty degrees and eighty degrees centigrade for a suitable period oftime such as between thirty and ninety seconds. Preferably, the surfaceof the plastic material is subjected to the bath for approximately oneminute at a temperature of eighty degrees centigrade. The sodiumhydroxide tends to attack the surface of the plastic material such asthe polyethylene terephthalate and hydrolyze the terephthalate chain soas to make the surface amenable to receiving the electroless deposition.By subjecting the surface of the plastic material to the previous steps,any tendency of the electroless deposition of magnetic material to flakefrom the surface of the plastic material is substantially eliminated,especially when the material is subsequently treated with theconcentrated solution of sodium hydroxide. It should be appreciated thatother materials than the concentrated solution of .sodium hydroxidecanbe used to etch the surface of the plastic material such asthepolyethylene terephthalate. For example, other alkalis can also be used.Afterthe surface of the plastic material such as polyethyleneterephthalate has been subjected to the concentrated solution ofsodium'hydroxide, it is washed in tap water for a suitable period oftime such as one minute. In this way, most of the sodium hydroxideremaining on the surface of the plastic material such as thepolyethylene terephthalate is removed. The surface of the plasticmaterial such as the polyethylene terephthalate is then ready to besubjected to the various baths for electrolessly depositing the magneticmaterial on the surface of the plastic material-As described above, thefirst bath may include stannousrchloride to obtain a reduced conditionon the surface of the plastic material. Preferably, the surface of theplastic material such as the polyethylene terephthalate is subjected totwo baths of stannous ions. The first bath tends toreact with any sodiumhydroxide remaining on the surface ofthe plastic material so as toremove this sodium hydroxide from the surface of the plastic material.Because of this, the first bath tends to become somewhat inefrectiverelatively quickly. The second bath of the stannous ions then actuallyoperates effectively to provide atreduction of the stannous salt on thesurface of the plastic material. After the first bath has becomesomewhat ineifective'relatively because of the reaction of the chemicalsin the bath with the sodium hydroxide remaining on the surface of thetape, the second bath may be used as the first bath and a new secondbath may be formed. By using two baths of stannous ions, any tendency tocreate magnetic dropouts (dead spots from a magnetic standpoint) on thesurface of the plastic material becomes minimized, especially in acontinuous deposition process. After the-surface of the plastic materialsuch as the polyethylene terephthalate has been subjected to a solutionof stannous ions, the surface of the plastic material is immersed in asolution of palladium ions as discussed above. This causes'a layer ofpalladium to be deposited on the surface of the plastic material. Thesurface of the plastic material such as the polyethylene terephthalatetape is then disposedin a bath for obtaining an electroless depositionof magnetic-materials on the surface of the plastic material. This bathmay have the following compositions by way of illustration:

(1) H =500;:B =6000 gauss thickness=20-30ainch 700 milliliters of water80-:grams of sodium citrate 40 grams of potassium sodium tartrate gramsof Versene complexing agent 10 grams of -sodium hypophosphite .100 gramsof 'CoSO (cobalt sulfate) 4grams of MnSO (manganese sulfate) 100milliliters of a 19% solution of ammonia in Water --for 5-5. /zmin. at80" C. pH maintained at' approx. 10.

(.2) -H 250; B =6000 gauss.

700 milliliters of water 80 grams of sodium critrate 40 grams ofpotassium sodium tartrate 10 grams of Versene ,10.grams-of sodiumhypophosphite 1 00,.grams of CoSO .7H O (cobalt sulfate) 3,4-grams ofFeSO (iron sulfate) for 55 /2 min. at 80 C. pH maintained approximately10.

j .The. hypophosphite salts in the solutions listed above constitutereducing agents to reduce the metallic. salts to metal. The citrate andtartrate salts serve as complexing agents in maintaining in solution thesalts of the magnetic materials in the plating bath for reduction by thehypophosphite ion. The citrate. and tartrate salts also serve asbuffers. Versene also serves as a complexing agent. The

ammonia serves to maintain the pH of the solution within particularlimits such as between eight and ten.

The surface ofv the plastic material is exposed to the electroless bathsfor suitable-periods of time such as 5 to 5 /2 minutes at anelevatedtemperaturesuch aseighty degrees centigrade. tUnder suchconditions, a magnetic layer of material is electrolessly deposited onthe surface of the plastic material such as the polyethyleneterephthalate tape with a suitable thickness such as. 20 to 30microinches.

The materials produced by the methods constituting this invention havecertain advantages over the prior art. One advantage is that themagnetic depositions electrolessly deposited on the surface of theplastic material such as the polyethylene terephthalate tape are firmlyadhered to such surfaces and do not tend to flake from the tape.Furthermore, the resistance of the electroless deposition to Wear tendsto be enhanced. For example, more than 100,000 error-free readings-havebeen obtained from materials which have been produced by the methodsconstituting this invention; furthermore, signal resolutions andmagnetic retentivities considerably greater than materials today on themarket have been obtained from materials produced by the methodsconstituting this invention. Packing densities of the magneticinformation recorded on the materials constituting this invention havealso considerably exceeded those of any materials now or previously onthe market. It can be noted that this modified process renders itselfvery well for a continuous tape-making process.

It will be appreciated that the methods described above may be used Withother plastic materials than polyethylene terephthalate. For example,the modified method described above has been used with some success todeposit magnetic materials by electroless techniques on a polyimidepolymer film designated as H Film by DuPont. The modified method hasalso been used with some success to deposit magnetic materials byelectroless techniques on the surface of a polycarbonate polymer filmdesignated as Lexan by General Electric. However, when the polycarbonatefilm is used as: the plastic material instead of the polyethyleneterephthalate, isopropyl alcohol is preferably used instead of sodiumhydroxide to remove the phenol residues of the film before theelectroless baths are applied.

After the electroless deposition of magnetic material has been formed onthe surface of the plastic material such as the polyethyleneterephthalate, a suitable materialmay be applied to the electrolessdeposition to provide a lubricating surface for the electrolessdeposition and to facilitate resistance to the Wear of the magneticheads by the magnetic alloy on the plastic material. For example, apolytetrafluoroethylene material having a fluorocarbon telomerdispersion and designated by the trademark Vydax b'y DuPont may be mixedwith a partially polymerized butyl titanate designated as Tyzor byDuPont to provide such a lubricating action. The material may be formedby a ratio of approximately one percent of Tyzor to ten to fifteenpercent of Vydax diluted with Xylol solvent (a benzene ring compound).The resultant material may be applied to the electroless deposition atroom temperature to provide the electroless deposition with a slipperysurface. The Tyzor material constitutes an adhesive for the Vydax so asto enhance the adhesion of the Vydax to the magnetic materialelectrolessly deposited on the tape. The lubricating material is appliedin a very thin layer so as to minimize the magnetic gap between the headand the electroless deposition on the surface of the plastic materialsuch as the polyterephthalate.

While I have described preferred embodiments of my invention, it isunderstood that various improvements may be made in the materials, inother matters, and in their reaction conditions disclosed Withoutdeparting from the spirit and scope of my invention as claimedhereinafter.

7 What is claimed is:

1. A process for converting a water-repellent surface of a plasticmaterial from a group consiting of a polyethylene terephthalate, apolyimide and a polycarbonate to a water-attractive surface and thenelectrolessly depositing a magnetic material on the water-attractivesurface of the plastic material, the process consisting essentially ofthe following steps:

treating the Water-repellent surface of the plastic material with aphenol solution,

washing the phenol from the treated surface of the plastic material,thereafter subjecting the treated surface of the plastic material to asolution of a material for etching the surfaces of the plastic materialand making the surfaces of the plastic material Water attractive,

disposing the plastic material in a bath of a stannous salt, thereafterdisposing the plastic material in a bath of a palladium salt, and

thereafter disposing the plastic material in a bath including salts ofat least one magnetic material from the group consisting of nickel,cobalt, iron and manganese, a complexing agent selected from a groupconsisting of citrates and tartrates and a hypophosphite to obtain adeposition of the magnetic material on the water-attractive surface ofthe plastic material. 2. A process according to claim 1 wherein thephenol solution is formed from 60% to 70% by weight of phenol to 30% to40% by weight of water and is applied for a period between 5 seconds and1 minute at a temperature between 40 C. and 65 C. and a concentratedsolution of sodium hydroxide in the range of 30% to 40% is used as theetchant and is applied for a period of time between 30 and 90 seconds ata temperature between 60 C. and 80 C.

3. In a process for converting a water-repellent surface of a plasticmaterial from a group consisting of polyethylene terephthalate, apolyimide and a polycarbonate to a water-attractive surface, the stepsof:

treating the plastic material with water-soluble phenol in a watersolution of a substance selected from the group consisting ofWater-soluble hydroxides and water-soluble carbonates of alkali andalkaline earth metals and mixtures thereof, and subjecting the resultingplastic material to the action of a Water solution of nitric acid. 4. Aprocess for converting a water-repellent surface of a plastic materialfrom a group consisting of polyethylene terephthalate, a polyimide and apolycarbonate to a water-attractive surface and applying an electrolessdeposition of a magnetic material to the water-attractive surface of theplastic material, the process consisting essentially of the followingsteps:

treating the water-repellent surface of the plastic material with aphenol solution to etch the surface,

subjecting the treated surface of the plastic material to a solutionhaving properties of dissolving into the solution any excess of phenolon the surface of the plastic material,

thereafter subjecting the treated surface of the plastic material to aconcentrated solution of sodium hydroxide to etch the surface of theplastic material and make the surface water-attractive,

thereafter subjecting the water-attractive surface of the plasticmaterial to at least one bath of a stannous salt,

thereafter subjecting the surface of the plastic material to a bath of apalladium salt, and

thereafter subjecting the surface of the plastic material to a bathwhich has a hypophosphite salt as a reducing agent, a buffering agentfrom a group con sisting of citrate and tartrate salts, ammoniumhydroxide as alkaline media and salts of magnetic materials from a groupconsisting of iron, nickel, cobalt and manganese to obtain anelectroless deposition of the magnetic materials on the surface of theplastic film. 5. A process for electrolessly depositing magneticmaterials on a surface of plastic materials from a group consisting ofpolyethylene terephthalate, a polyimide and a polycarbonate, the processconsisting essentially of the following steps:

applying a phenol solution to the water-repellent surface of the plasticmaterial where the phenol has properties of constituting a solvent forthe plastic material,

removing any excess of the phenol from the waterrepellent surface of theplastic material, applying a solution of an alkali to the surface of theplastic material to etch the surface of the plastic material and makethe surface water-attractive,

removing any excess of the alkali from the waterattractive surface ofthe plastic material,

thereafter applying a solution of stannous chloride to the etchedsurface of the plastic material, thereafter applying a palladiumchloride solution to the surface of the plastic material, and

thereafter applying an electroless plating solution including abuffering agent from a group consisting of a tartrate and a citrate, ahypophosphite as a reducing agent, ammonium hydroxide as an alkalinemedia and salts of a magnetic material from a group consisting of iron,nickel, cobalt and manganese.

6. A process according to claim 5 wherein the phenol solution is formedfrom 60% to 70% of phenol by weight in 30% to 40% by weight of water andwherein the alkali material constitutes sodium hydroxide having aconcentration of 30% to 40% by weight in 60% to 70% by Weight of water.

7. A process for converting a water-repellent surface on a plasticmaterial from a group consisting of polyethylene terephthalate, apolyimide and polycarbonate to a water-attractive surface and applyingan electroless deposition of a magnetic material to the Water-attractivesurface of the plastic material, the process consisting essentially ofthe following steps:

treating the water-repellent surface of the plastic material with aphenol solution to convert the waterrepellent surface into awater-attractive surface; thereafter treating the water-attractivesurface of the plastic material with a solution having properties ofwashing into the solution any of the phenol remaining on thewater-attractive surface of the plastic material; applying a reducingagent to the water-attractive surface of the plastic material tochemically reduce this surface; and

applying to the water-attractive surface of the plastic material, for asufiicient period of time to obtain the deposition of the magneticmaterials on the waterattractive surface, an electroless bath which hasthe magnetic material, a reducing agent to reduce the'ions of themagnetic material and a complexing agent to prevent the precipitation ofthe magnetic material from the bath.

8. A process for converting a water-repellent surface of a plasticmaterial from a group consisting of a polyethylene terephthalate, apolyimide and a polycarbonate to a water-attractive surface and applyingan electroless deposition of a magnetic material to the water-attractivesurface of the plastic material, the process consisting essentially ofthe following steps:

treating the water-repellent surface of the plastic material with aphenol solution to make the surface water-attractive;

thereafter treating the plastic material with a substance selected froma group consisting of water-soluble hydroxides of alkali and alkalineearth metals and water-soluble carbonates of alkali and alkaline earthmetals to remove from the water-attractive surface 9, of the plasticmaterialanyphe'nol deposited on this surface; t a

thereafter applying to the surface of the plastic material a solutionhaving properties of making the sur- 7 face of the plastic materialwater-attractive;

applying to the water-attractive surface of the plastic material astannous batht'o chemically reducethis surface; i applying to thechemically reduced surface of the plastic material a palladium bath tosensitize this surface; and i applying, for a controlled period of timeto obtain the deposition of the magnetic material on the sensitizedsurface, to the sensitized surface of the plastic material anelectroless bath which has the magnetic material, a reducing agent toreduce themagnetic material and a complexing agentjto prevent theprecipitation of the magnetic material in the electroless bath. 7 9. Theprocess set forth in claim 8 wherein the magnetic material in theelectroless bath is selected from a group consisting of cobalt, nickel,iron and manganese and wherein the reducing, agent in the electrolessbath consistitutes a hypophosphite and wherein the complexing agent inthe electroless bath is selected from a group consisting of citrates andtartrates and wherein the phenol solution has a concentration ofapproximately 60% to 70% by weight of phenol and 30% to 40% by Weight ofwater and the concentrated solution of sodium hydroxide and wherein thesolution having the properties of making the surface of the plasticmaterial has a concentration of approximately 30% to 40% by weight ofsodium hydroxide and approximately 60% to 70% by weight of water.

10. A process for converting a water-repellent surface of a plasticmaterial from a group consisting of polyethylene terephthalate, apolyirnide and a polycarbonate to a water-attractive surface andapplying an electroless deposition of a magnetic material to thewater-attractive surface of the plastic material, the process consistingessentially of the following steps:

treating the Water-repellent surface of the plastic material with aphenol solution to etch this surface;

applying to the water-repellent surface of the plastic material asolution having properties of dissolving into the solution any phenoldeposited on the surface;

applying to the water-repellent surface of the plastic material asolution having properties of making waterattractive the water-repellentsurface of the :plastic material;

applying to the water-attractive surface of the plastic material a bathhaving properties of sensitizing this surface; and

applying to the sensitized surface of a plastic material an electrolessbath which has the magnetic material, a reducing agent to reduce ions ofthe magnetic materials and a complexing agent to prevent theprecipitation of the magnetic material in the electroless bath.

11. The process set forth in claim 10 wherein the bath for makingwater-attractive the water-repellent surface of the plastic materialconstitutes a concentrated solution of sodium hydroxide.

12. The process set forth in claim 11 wherein a bath is applied to thewater-attractive surface of the plastic material to chemically reducethis surface before the surface is sensitized.

13. A process for converting a water-repellent surface of a plasticmaterial from a group consisting of a polyethylene terephthalate, apolyimide and a polycarbonate to a water-attractive surface and applyingan electroless deposition of a magnetic material to the water-attractivesurface of the plastic material, the process consisting essentially ofthe following steps:

treating the water-repellent surface of the plasticmaterial with aphenol solution to etch thissurface; applying to the water-repellentsurface of the plastic material a solution having properties ofdissolving into the solution any phenol deposited on the solution;applying to the Water-repellentsurface of the-plastic material aconcentratedsolution of sodium hydroxide with properties of makingwater-attractive the waterrepellent surface of the plastic material;applying to the water-attractive surface of the plastic material apalladiumbath for sensitizing this surface; and A applying to thesensitized surface of the plastic mate rial an electroless bath whichhas the magnetic material, a reducing agent to reduce themagneticmaterial and a complexing agenttoprevent the precipitation ofthe magnetic material in the electroless bath. t 14. Theprocess setforth in claim'13 wherein the phenol solution constitutes phenol andwater in the ratio of 60 to 70 parts by weight of phenol to 30 to 40parts by weight of water and'wherein a stannous bath-is applied to thewater-attractive surface of the plastic material to chemically-reducethis surface before the surface is sensitized by the palladium bath. r

15. The process set forth in claim 14 wherein the magnetic material inthe electroless bath is selected from elements in a group consisting ofiron, cobalt, nickel and manganese, the reducing agent in theelectroless bath constitutes a hypophosphite and the complexing agent inthe electroless bath is selected from a group consisting of citrates andtartrates and wherein the phenol solution constitutes phenol and waterin the ratio of 60 to 70 parts by Weight of phenol to 30 to 40 parts byweight of Water.

16. The process set forth in claim 15 wherein a stannous bath is appliedto the Water-attractive surface of the plastic material to chemicallyreduce this surface before the surface is sensitized by the palladiumbath and wherein the phenol solution is applied to the surface of theplastic material at a temperature between approximately 40 C. and 65 C.for a period of time between approximately 5 seconds and 1 minute andwherein the concentrated solution of sodium hydroxide containsapproximately 30% to 40% by weight of sodium hydroxide and the remainderby weight of water.

17. A process for converting a Water-repellent surface of a plasticmaterial from a group consisting of a polyethylene terephthalate, apolyimide and a polycarbonate to a water-attractive surface and applyingan electroless deposition of a magnetic material to the water-attractivesurface of the plastic material, the process consisting essentially ofthe following steps:

treating the water-repellent surface of the plastic material with aphenol solution; washing from the water-repellent surface of the plasticmaterial any excess of phenol with a solution having properties ofdissolving the phenol into the solution;

thereafter subjecting the treated surface of the plastic material to aconcentrated solution of sodium hydroxide to etch the surface of theplastic material and make the surface water-attractive; washing from thewater-attractive surface of the plastic material any excess of sodiumhydroxide;

subjecting the Water-attractive surface of the plastic material to asolution having properties of chemically reducing the surface;

subjecting the reduced surface of the plastic material to a solutionhaving properties of sensitizing the surface; and

subjecting the sensitized surface of the plastic material,

for a sufficient period of time to obtain a deposition on the sensitizedsurface of the plastic material, to an electroless bath which has themagnetic material, a reducing agent for obtaining a deposition of themagnetic material on the sensitized surface and a 11 complexing agentfor preventing the precipitation of the magnetic material in theelectroless bath. 18. The process set forth in claim 17 wherein thephenol solution contains 60% to 70% by weight of phenol and to by weightof water and wherein the solution of sodium hydroxide contains 30% to40% by weight of sodium hydroxide and the remainder by weight of water.

19. The process set forth in claim 18 wherein the solution havingproperties of chemically reducing the surface is stannous, the solutionhaving properties of sensitizing the surface primarily containspalladium and the magneticmaterial in the electroless bath is selectedfrom a group consisting of iron, cobalt, nickel and manganese, thereducing agent in the electroless bath is a hypophosphite and thecomplexingagent in the electroless bath is selected from a groupconsisting of citrates and tartrates.

20. The processset forth in claim 19 wherein the phenol solution isapplied to the surface at a temperature between approximately 40 C. andC. for a period of time between approximately 5 seconds and one minuteand the solution of sodium hydroxide is thereafter applied at atemperaturebetween approximately 60 C. and C. for a period of timebetween approximately 30 seconds and seconds.

References Cited UNITED STATES PATENTS Crehan 117 47 Emerson 1l747Nelson et al. 117-76 Kelley 117-47 Hookway et al. 117 -47 Chapman 41- 41Foley 117 47 Koretzky etal. 11,7-47 Wenner v 29- Edwards 26078 Frantzen156-7 Nadeau et al. 9687 Tsu et al. -Q 11 7 54 Chilton et al. f1 1,747

Bruner 15 6 2 FOREIGN PATENTS I Great Britain. Canada.

WILLIAM MARTIN, Primary Examiner. 25 W. D. HERRICK, Assistant Examiner.

